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HOW TO cheat IN Photoshop CS5
The art of creating realistic photomontages
By Steve Caplin
Focal Press Copyright © 2010 Steve Caplin
All right reserved.
Chapter One Natural selection
The Techniques described in this book assume you have a reasonable working knowledge of Photoshop. In later chapters, we'll discuss ways of working that involve modifying selections, and using both QuickMask and the Pen tool to create Bézier curves. The first part of this chapter will serve as a refresher course on these fundamental techniques for those who already know them, and will introduce the concepts for those who have not yet experimented with them.
Later on, we'll go into more detail on how to work with and modify layers and colors without having to pick up a brush first: there are many techniques, such as those for changing colors selectively, that can be accomplished entirely by means of dialog boxes.
Selection: the fundamentals
ALL PHOTOSHOP WORK begins with making selections. Shown here are some of the basic keyboard shortcuts that every Photoshop user should be able to use as second nature: even if you hate learning keyboard commands, you owe it to your productivity and your sanity to learn these.
Temporarily accessing the Move tool, using the shortcut shown in step 8, works when any other tool is active — not just the selection tools. This makes it easy to move any layer around while painting, selecting or using type, without having to reach for the toolbar.
1 Normal drawing with the Marquee tool is from corner to corner. But if you're using the Elliptical Marquee, it's hard to conceive where the 'corner' might be. Hold down [??][alt] after you begin drawing to draw from the center outwards. The selected region is shown above, in each case.
2 If you hold [??][alt] before you draw a second selection, you will remove this selection from the original one. Be sure to press this key before you begin drawing, or you'll simply draw from the center. Here, we've deselected the center of the hubcap, leaving just the rim.
3 Holding [??][alt] subtracts from the selection, but holding [Shift] adds to it. Again, be sure to hold the key before you begin drawing. By holding this key down, we're able to add back the middle knob on the hubcap from the section we'd previously deselected.
4 Here's what happens if we combine the two keys. Holding [??][Shift][alt][Shift] intersects the new selection with the previous one, resulting in just the overlap between the two. Here, the original elliptical selection is intersected with the new rectangular selection.
5 A little-known modifier is the Space bar, which performs a unique task: it allows you to move a selection while you're drawing it, which is of enormous benefit when selecting areas such as the ellipse of the hubcap. Here, we've used the technique to move the selection over to the side.
6 If you drag a selected area with a selection tool active (Marquee, Lasso etc), you'll move the selected region but not its contents.
7 To access the Move tool temporarily, hold [??][ctrl] before you drag. Now, the selection itself will be moved when you drag it.
8 Holding down [??][alt] as well will move a copy, leaving the original selection where it was — but be sure to hold the modifier before dragging.
9 To constrain the movement to exactly vertical or horizontal, hold the [Shift] key after you've started to drag the selection.
10 You can continue to make several copies by releasing and holding the mouse button while holding the [??][alt] key down.
Selections can be nudged with the arrow keys, as well as being dragged into position — useful for aligning them precisely. One tap of the arrow keys will move a selection by a single pixel. If you hold the [Shift] key as you tap the arrow, the selection will move by 10 pixels at a time. If you also hold [??][ctrl] you'll move the contents, rather than just the selection boundary.
The Lasso and Magic
THE LASSO MAY WELL have been the first selection tool to be seen in a digital paint program, having put in its initial appearance 20 years ago, but these days it's far from being the ideal tool. Clumsy and inaccurate to draw with, it's best reserved for tidying up selections made in other ways, as we'll see here.
There is one surprising use for the Lasso tool, however, and that's for tracing straight lines — thanks to a little-known keyboard shortcut. We'll look at this technique in steps 6 and 7.
The Magic Wand tool is a great all-purpose tool for selecting areas of a similar tonal range, and is widely used for removing simple backgrounds. Its tendency to 'leak' into areas you don't want selected, however, means you have to pay close attention to what's actually been selected — and be prepared to fix it afterwards.
1 This straightforward scene should be an ideal candidate for Magic Wand selection: after all, it's on a plain white background. But even simple selections can have their pitfalls.
2 Begin by clicking in the white area outside the two figures. (Note that the main image has been knocked back so we can see the selection outlines more clearly.)
3 The area between the men's legs was not included in the original selection, so we need to hold the [Shift] key and click there to add it to our selection area.
4 So far, we've selected everything except the bodies. We need to inverse the selection, by pressing [??][Shift][I][ctrl][Shift][I], to select the bodies themselves.
5 Note how the original Magic Wand selection 'leaked' into the paper and the shirt collars. This is easily fixed by holding [Shift] as we add those areas with the Lasso tool.
6 Although the Lasso tool may seem the obvious choice when drawing freehand selections, it can also be used to select objects made of straight lines, such as this fence. Hold the [??] [alt] key and then click once at each corner of each vertical post, clicking additionally from the bottom of one to the bottom of the next. You can also use the Polygonal Lasso tool to do this job on its own, without holding the modifier key.
7 Now to add the horizontals. Hold the [Shift] key and then, after clicking the first corner point, add the [??][alt] key and continue to click each corner as before. Be sure not to hold [??][alt] before beginning to click or its effect will be to subtract the new selection from the old one, rather than adding to it — see the previous page for details on how these modifier keys work. The fence will now be fully selected.
The tolerance setting of the Magic Wand affects the extent to which it includes similar colors. The higher the tolerance, the wider the range of shades it sees as being similar to the one you click on. For general use, set a tolerance of 32 and adjust if necessary.
QuickMask 1: better selection
QUICKMASK IS THE MOST POWERFUL tool for creating selections in photoshop. It uses a red overlay to show the selected area, allowing you to see the image through it; when you leave QuickMask mode, the painted area will be selected.
In QuickMask, painting with black will add to the selection and painting with white will subtract from it (as long as you're set up as described below). This makes it easy to trace around any object: it's far quicker and more controllable than the lasso tool, and in situations such as the one shown here it's the best solution.
The default setting is for QuickMask to highlight the masked (unselected) areas with a red overlay, leaving the selected areas transparent: I find it far preferable to work the other way around, so that the selected areas are highlighted. To change the settings, you need to double-click the QuickMask icon (near the bottom of the toolbar, just below the foreground/background color swatches) and use the settings shown above.
1 This image would be tricky to select using the Lasso tool, and impossible with the Magic Wand — the background and foreground are just too complex. Press [Q] to enter QuickMask mode so we can begin.
2 Using a hard-edged brush, begin to trace around the inside of the figure. You don't need to paint the whole figure in one go, so take it at your own pace and let the mouse button up every now and again to take a break.
3 It's easy to make a simple mistake when painting the outline, such as going over the edge by accident — as I've done at the elbow here. Don't simply press Undo, or you'll lose the whole brush stroke; there's a better way to correct the error.
4 To paint out the offending selection area, change the foreground color from black to white (the keyboard shortcut to do this is [X]). Paint over the mistake, then press [X] again to switch back to black to paint the rest of the selection.
5 You don't need to worry too much about fine detail at this stage — just get the basic figure highlighted. Fiddly areas, such as around the ear and the collar, can be left till later.
6 With the basic outline selected, we can address the detail. Lower the brush size using [ until you have a size that's small enough to paint in the outline detail comfortably.
7 Now the outline is selected, leave QuickMask by pressing [Q] again, and the selection will be shown as a familiar 'marching ants' outline. You can now press [??][J][ctrl][J] to make a new layer from the selection.
8 When the background is removed, we can see more clearly that the right side of the image is in really deep shadow — too deep to work with. Again, we can use QuickMask to select the shadow area.
9 Enter QuickMask again by pressing [Q], and this time change to a soft-edged, larger brush. When we paint over the shadows now, we're creating a soft-edged selection; then leave QuickMask with [Q] again.
10 Because our selection has a soft edge, we can use any of the standard Adjustments to lighten up the shadow area (I've used Curves here) without showing a hard line between the changed and unchanged areas.
You can mix hard and soft brushes within the same QuickMask session. For example, if you're cutting out a picture of a dog, you might use a soft-edged brush to trace around the fur, and a hard-edged brush to trace the outline of the nose and mouth. Soft brushes are the equivalent of feathering Lasso selections, but are very much more controllable.
QuickMask 2: tips and tricks
QUICKMASK IS THE BEST TOOL FOR making complex selections, especially of natural or organic objects where there are no hard, straight edges. By switching between large and small brushes, it's easy to trace even the most fiddly of objects with a little patience.
It all becomes more interesting when we look at using shades other than pure black and white to paint the mask. By painting with gray, we create a mask which is semi-transparent: the darker the shade, the more opaque the resulting selection will be. This technique is of particular benefit when selecting objects such as this fly, which has an opaque body and legs but semitransparent wings. Building that transparency into the selection makes the whole effect far more convincing when we place the fly on a new background: the lowered opacity makes it look far more as if it belongs in its new surroundings.
1 Enter QuickMask mode with [Q]. Begin by using a hard-edged brush to trace around the main body of the fly. Don't worry about the legs at this stage — we'll add them in later. Remember that if you make a mistake, you can always swap the foreground color to white and paint it out.
2 We could just paint in the middle of the body — but with a large selection, that would take a while. Here's a shortcut: use the Magic Wand tool to select the middle portion, then expand that selection (Select menu) by, say, 4 pixels to make sure the edges are covered.
3 Now fill that new selection with the foreground color (the shortcut for doing this is [??]←[alt]←) and then deselect ([??][D][ctrl][D]) to remove the Magic Wand selection. This is a useful technique for large images in particular.
4 Now for the legs. Switch to a much smaller (but still hard-edged) brush, and trace each leg carefully. You can change brush sizes by using ] to go to the next size up, and [ to go to the next size down.
5 Before painting the wing area, we need to switch from black to a dark gray color to give the wings their transparency. Choose a gray from the Swatches panel, and, with a bigger brush, paint over the wings.
6 The wings may need to be semi-transparent, but those fine legs shouldn't be — so switch back to black (press [D]) and, with a small brush, paint in the legs where they're seen through the wings.
7 Now exit QuickMask by pressing [Q] again, and press [??][J][ctrl][J] to make a new layer from this selection. When we hide the underlying layers, we can see a few small errors: a bit of background has crept into the wings.
8 The easiest way to fix this is simply to erase the offending areas with a hard-edged Eraser. If you prefer, you could go back to QuickMask and tidy it up there, but it generally isn't worth the extra effort.
9 Because we selected the wing area using built-in transparency, we can partially see through them when we place the fly on a different background, adding greatly to the realism of the scene.
Why didn't we simply paint with a lower brush opacity in step 5, rather than switching to gray? Because if we had, we would have to have painted the whole of each wing in a single brushstroke, without interruption. Otherwise, the new stroke would overlap the old one, creating a darker area (and so a stronger opacity) in the intersection.
QuickMask 3: transformations
AS WELL AS USING PAINTING TOOLS, you can use any of the standard transformation tools within QuickMask. This can make it easier to select tricky areas, such as the angled hubcaps on this sports car. Even though the hubcap is an ellipse, the angle at which it's been photographed makes it impossible to select with the standard elliptical Marquee tool. QuickMask, however, makes short work of the problem.
QuickMask can be used for creating all kinds of shapes from scratch. Hard-edged rectangles and smooth circles can be combined to build lozenge shapes far more quickly than toying with the radius settings of the shape tools, for example.
There are many more uses to QuickMask than are shown here. Get into the habit of using it for your everyday selections, and you'll find it quickly repays the effort.
1 The hubcap on this car is a perfect circle photographed from an oblique angle. The Elliptical Marquee tool, however, only works on an orthogonal axis — there's no way to make it draw at an angle, as would be required here.
2 To begin, use the Elliptical Marquee tool to draw a circle anywhere on the image (hold the [Shift] key as you draw to constrain the ellipse to a circle). If you can't find the Elliptical Marquee tool, click and hold on the regular Marquee tool in the toolbar and it will pop open for you.
3 Now enter QuickMask mode by pressing [Q]. The circle you just drew will appear as a solid red circle, which will show us exactly where our selection edges lie in the illustration.
4 Enter Free Transform mode by pressing [??][T][ctrl][T], and selection borders will appear around the circle — no need to make an additional selection first. Drag the circle so one edge touches the edge of the hubcap, and rotate it to roughly the right angle.
5 Now pull in the opposite handle so it touches the opposite rim of the hubcap, and do the same with the top and bottom edges. At this point, you may need to adjust the angle of rotation of the ellipse so it matches the hubcap perfectly.
Excerpted from HOW TO cheat IN Photoshop CS5 by Steve Caplin Copyright © 2010 by Steve Caplin. Excerpted by permission of Focal Press. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
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